Coated fibrous pipe insulation system

ABSTRACT

A pipe insulation system includes a tubular core of fibrous insulation and a flexible closed cell foam layer overlaying the core and forming an outer surface of the system. The tubular core has a first longitudinal slit extending completely through the wall of the core and a second longitudinal slit in the inner surface of the tubular core, opposite the first slit, that forms a hinge permitting the tubular core to be opened and closed to place the system about a pipe. Preferably, the foam layer has a water vapor permeance rating of 0.02 perms or less and the pipe insulation system includes a seal for sealing the first slit so that an outer surface layer of the sealed system formed by the foam layer and seal has a water vapor permeance rating of 0.02 perms or less.

This patent application is a continuation-in-part of patent applicationSer. No. 10/449,781 filed on May 30, 2003 now U.S. Pat. No. 6,782,922.

BACKGROUND OF THE INVENTION

The subject invention relates to a coated pipe insulation system and inparticular, to a coated pipe insulation system that includes a tubularcore of fibrous insulation and a flexible closed cell foam layer thatoverlays and is bonded to an outer surface of the tubular core. The pipeinsulation system of the subject invention is especially well suited forinsulating cold pipe systems.

Fiberglass pipe insulation, such as fiberglass pipe insulation marketedby Johns Manville International, Inc. under the trade designationMicro-Lok® pipe insulation, is a preformed tubular insulation used toinsulate pipe ranging in nominal diameter from about 0.5 inches to about30 inches. The pipe insulation typically comes in 36 inch (0.92 m) longsections with wall thicknesses ranging from about 0.5 inches (13 mm) to6 inches (152 mm) and in densities ranging from 3 to 6 pcf (0.48 to 0.96grams/cc). Each pipe insulation section has a first longitudinallyextending radial slit extending completely through the tubular wall anda second longitudinally extending radial slit, opposite the first slit,that extends only part of the way through the tubular wall to form ahinge that allows the pipe insulation section to be opened, placed over,and closed about a length of pipe.

These fiberglass pipe insulation sections are typically produced withcoverings that are adhesively bonded to the outer surfaces of thesections with an adhesive that typically is a hot melt adhesive. Thecoverings are typically made of paper-scrim-foil or paper-scrim-MPETwhere MPET is polyethylene terephthalate with vacuum-sputtered aluminumdeposited on at least one surface of the film. The coverings(hereinafter referred to as “jackets”) perform multiple functions:

-   -   the jackets contain and protect the fiberglass insulation core;    -   the jackets generally provide an acceptable finished appearance,        i.e. a generally smooth, white matte finish with subtle scrim        lines visible through the paper;    -   the jackets retard water vapor transmission into the fiberglass        insulation core, generally with a water vapor transmission test        value of 0.02 perms or lower, as tested to ASTM E 96 standard,        but do not provide a barrier to water vapor transmission into        the fiberglass insulation core; and    -   the jackets provide a means to secure the pipe insulation to        itself with a tape or other mechanical fastener that engages the        jacket.

When cold pipe systems are being insulated with these jacketedfiberglass pipe insulation sections or other jacketed fibrous pipeinsulation sections, special precautions must be taken to keep watervapor form condensing from the atmosphere onto the cold pipe. ASTM C755, Section 4.1, states:

-   -   “Experience has shown that uncontrolled water entry into thermal        insulation is the most serious factor causing impaired        performance. Water entry into an insulation system may be        through diffusion of water vapor, air leakage carrying water        vapor, and leakage of surface water. Application specifications        for insulation systems that operate below ambient dew-point        temperatures should include an adequate vapor barrier system.”        Cold pipe systems are considered to be those systems where the        temperature of the fluid in the pipe is between 35° F. and        65° F. Because ambient conditions in many areas of the United        States can commonly result in dew points that are higher than        the pipe temperatures, condensation of water vapor can occur in        these cold systems. Condensation on the outside of the jacketed        pipe insulation sections can contribute to liquid water damage        or microbial growth, and condensation on the inside of the        jacketed pipe insulation sections can contribute to corrosion of        the pipe and a loss of thermal insulation efficiency.

To inhibit condensation from accumulating in these cold pipe systems,the pipe insulation must be installed with a wall thickness sufficientto maintain the outer surfaces of the jacketed fibrous pipe insulationsections warmer than the dew point. If the jacketed fibrous pipeinsulation sections do not have sufficient thickness to maintain theouter surfaces of the jacketed fibrous pipe insulation sections abovethe dew point, condensation will occur on the outside of the jacketedfibrous pipe insulation sections. In addition to the thicknessrequirement, a water vapor barrier layer [referred to as a “Type I”vapor barrier in ASTM C 921-89 (reapproved 1996)] has customarily beenused to cover the jacketed fibrous pipe insulation sections to keepwater vapor from condensing on the outer surface of the jacketed fibrouspipe insulation and migrating into the insulation where it wouldcondense.

Since current jacketed fibrous pipe insulation does not provide a watervapor barrier, if jacketed fibrous pipe insulation is to be installed oncold pipe systems in an unconditioned space, current industry practicesrecommend that a post-applied layer of PVC (a PVC jacket) be installedover the jacketed fibrous pipe insulation sections to keep water vaporout of the cold pipe insulation system. The PVC jacket must be sealedwith either tape or solvent based welding products. This is the mostcommon way to get a vapor barrier layer that meets the ASTM C 921 Type Istandard. However, with this method, the installers must first installthe jacketed fibrous pipe insulation and then go back over the entirejob a second time to install the PVC jackets over the jacketed fibrouspipe insulation. Thus, this method of sealing cold pipe insulationsystems is both expensive and time consuming.

In addition to the need to enclose the jacketed fibrous pipe insulationsin PVC jackets when the jacketed fibrous pipe insulations are applied tocold pipe systems, the use of jacketed fibrous pipe insulations maypresent other problems. While jacketed fibrous pipe insulationsgenerally provide an acceptable appearance, the appearance of thejackets on such pipe insulations can be degraded under certainconditions. The jackets of fibrous pipe insulations are not an integralpart of the insulation cores, but, typically, are only bonded to thefibrous insulation cores on each side of the longitudinally extendingopening formed in the fibrous cores by the longitudinal slits in thecores. Since the jackets are only bonded to the fibrous cores along theopenings formed by the longitudinal slits, rough handling, contact withpipe hangers, butt strip application (joining and sealing adjacentpieces of pipe insulation), etc., may cause deformations in the jackets,such as wrinkling or dimpling, at locations where the jackets are notdirectly adhered to the fibrous cores. In addition, the absorption ofwater by some jackets under humid conditions may also cause the jacketsto wrinkle or dimple.

The installation of jacketed pipe insulations can also present problems.During the installation of pipe insulation, an installer has to navigatearound numerous obstructions such as pipe hangers, valves, elbows,flanges, etc. Normally, the jacketed pipe insulation must be cut to fitthe jacketed pipe insulation to the pipe system so that the jacketedpipe insulation accommodates these obstructions. As discussed above,current fibrous pipe insulations have jackets that are adhered to thefibrous cores with lines of adhesive on each side of the longitudinalopenings formed by the slits in the fibrous cores. Frequently, theselines of adhesive are not adequate to hold the jackets in place on thecores during and after the cutting of the jacketed fibrous pipeinsulations. Some installers resort to stapling the jackets to the coresnear the locations of the planned cuts in order to secure the jackets tothe cores during and after cutting. This procedure increases the timefor installation and breaches the vapor retarding jackets. Sometimes,after cutting pipe insulations, the installer will need to trim thejackets with scissors to provide the jackets with a clean uniformappearance after installation. Again, this extra installation stepincreases the time required for installation.

Recently, a fiberglass pipe insulation has been introduced that does notblock the passage of water vapor, but utilizes a wicking membranesituated around the inside of the fiberglass pipe insulation section. Intheory, this membrane is supposed to carry liquid water, which hascondensed at the cold pipe surface, back to the outer surface of thepipe insulation section (using capillary action and gravity) where theliquid water is supposed to evaporate. However, these wicking systemsare expensive and the installation of these wicking systems requires theexercise of special care. In addition, since liquid water is placed incontact with the outer surface of the cold pipe in these systems, theeffectiveness of the system is variable and highly dependent uponambient temperature and relative humidity. In general, these systemstend to be more effective in low humidity environments and lose theireffectiveness in ambient conditions approaching 90° F. and 90% humidity.

Alternative pipe insulation systems to fiberglass pipe insulationsystems exist for insulating cold pipe systems. These alternativesystems do not have fibrous tubular cores and are mainly closed-cellinsulation materials, such as cellular glass, polyisocyanurate foam,rubber, and similar products. However, these products tend to beexpensive, time consuming to install, and are prone to installationerrors or system breaches.

SUMMARY OF THE INVENTION

The subject invention provides a solution to the problem of insulatingcold pipe systems by providing a coated fibrous pipe insulation systemthat in a preferred embodiment does not require an auxiliary outer PVCjacket to provide the system with a water vapor barrier. The coatedfibrous pipe insulation of the subject invention does not requirestapling to hold the coating in place during and after cutting or theuse of scissors to give the coated fibrous pipe insulation a cleanuniform appearance after the coated fibrous pipe insulation has been cutduring installation. In addition, the coating of the coated fibrous pipeinsulation of the subject invention will not be prone to wrinkling ordimpling.

Each pipe insulation section of the coated fibrous pipe insulationsystem of the subject invention has a tubular fibrous insulation corecoated with a flexible closed cell foam layer that is coextensive withand bonded to the substantially cylindrical outer surface of the tubularcore. The wall of the tubular core has a first longitudinal slitextending completely there through and a second longitudinal slit in theinner surface of the tubular core that is substantially opposite thefirst slit and extends only partially through the wall of the tubularcore to form a longitudinally extending hinge in the tubular core thatpermits the tubular core to be opened, placed over, and closed about alength of pipe. Preferably, the coating layer on the coated fibrous pipeinsulation sections of the subject invention as applied to a pipe systemhas a water vapor permeance rating of 0.02 perms or less and, morepreferably, functions as a water vapor barrier. Preferably, the coatedfibrous pipe insulation sections of the subject invention are held andsealed about a pipe with an adhesive strip, a solvent weld, or anadhesive material or coating. Preferably, the coated fibrous pipeinsulation sections have a thickness and thermal conductivity, for atemperature between 35° F. and 65° F. at the inner surface of the coreand a temperature of 90° F. and a relative humidity of 90% at the outersurface of the core, that locates the dew point within the wall of thecore at a location spaced from both the inner and outer surfaces of thecore wall.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a coated fibrous pipe insulation sectionof the subject invention with the section partially opened.

FIG. 2 is an end view of the coated fibrous pipe insulation section ofFIG. 1 installed on a pipe and held in the fully closed position by anadhesive strip.

FIG. 3 is an end view of the coated fibrous pipe insulation section ofFIG. 1 installed on a pipe and held in the fully closed position by anadhesive coating or solvent weld.

FIG. 4 is an end view of the coated fibrous pipe insulation section ofFIG. 1 installed on a pipe and schematically showing the location of dewpoint within the wall of the section.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, each preformed coated fibrous pipe insulationsection 20 of the coated fibrous pipe insulation system of the subjectinvention has a tubular fibrous insulation core 22 with substantiallycylindrical inner and outer surfaces and a flexible closed cell foamlayer 24 that is coextensive with and bonded to the substantiallycylindrical outer surface of the tubular core. The wall of the tubularcore 22 has a first longitudinally extending radial slit 26 extendingcompletely there through and a second longitudinally extending radialslit 28 in the inner surface of the tubular core 22 that issubstantially opposite the first slit 26 and extends only partiallythrough the wall of the tubular core 22 to form a longitudinallyextending hinge 30 in the tubular core that permits the tubular core 22to be opened, placed over, and closed about a length of pipe. Typically,the slit 28 extends between one half and three quarters of the waythrough the wall of the core.

The coated fibrous pipe insulation sections 20 are typically used toinsulate pipes 32 ranging in nominal diameter from about 0.5 inches toabout 30 inches. The coated fibrous pipe insulation sections 20typically comes in 36 inch (0.92 m) long sections with wall thicknessesranging from about 0.5 inches (13 mm) to 6 inches (152 mm) and indensities ranging from 3 to 6 pcf (0.48 to 0.96 grams/cc). While otherfibrous insulations may be used to form the fibrous insulation core 22such as, but not limited to, mineral wool, the preferred fibrousinsulation forming the insulation core 22 is fiberglass insulation.

The closed cell foam layer 24 contains and protects the fibrous core 22and may be made of various flexible polymeric closed cell foam materialssuch as but not limited to a rubberized closed cell foam insulationmarketed by Armacel under the trade designation “ARMAFLEX”. Preferably,the closed cell foam layer 24 is white with a smooth, durable outersurface. The closed cell foam coating layer 24 may be applied to theouter surface of the core 22 by any suitable method such as, but notlimited to, spraying, extrusion coating, pultrusion coating, or othermethods and may be applied in a single or multiple step process. Theclosed cell foam layer 24 must be flexible so that the fibrous pipeinsulation section 20 can be flexed open about hinge 30 and closed abouta pipe without cracking and preferably, without even forming a permanentcrease. Preferably, the closed cell foam layer 24 is dimensionallystable, especially when subjected to diverse levels of ambienttemperature and humidity, and has good stability in moist or steamyenvironments where the fibrous pipe insulation section 20 will beinstalled such as, but not limited to, those found in mechanical rooms,boiler rooms, and other environments with the potential for steam andhigher ambient temperatures. Preferably, the closed cell foam layer 24should be cuttable with a non-serrated knife and should not deteriorate,delaminate, or crack under normal service conditions.

Preferably, the fibrous pipe insulation section 20 has a composite flamespread and smoke developed rating equal to or less than 25/50 asmeasured by the ASTM E 84-01 tunnel test method, entitled “Standard TestMethod for Surface Burning Characteristics of Building Materials”,published July 2001, by ASTM International of West Conshohocken, Pa.

Preferably, the closed cell foam layer 24 contains additives such as,but not limited to, UV stabilizers and antimicrobial agents and/or fungigrowth inhibiting agents. An example of a fungi growth-inhibiting agentis the fungi growth resistance additive 2-(4-Thiazolyl)Benzimidazole,also known as “TBZ”. Multiple forms of TBZ are available for specificapplications in polymers, adhesives, coatings and additives. One exampleof the fungi growth resistance additive is available from Ciba SpecialtyChemicals under the trade designation Irgaguard F-3000 fungi growthresistance additive. It is believed that the inclusion of the IrgaguardF-3000 fungi growth resistance additive in amounts between 0.05% and0.5% by weight of the materials in the polymeric coating 24 of thecoated fibrous pipe insulation sections 20 will effectively inhibitfungi growth. Examples of other antimicrobial, biocide fungigrowth-inhibiting agents that may be used are silver zeolyte fungigrowth inhibiting agents sold by Rohm & Haas Company under the tradedesignation KATHON fungi growth-inhibiting agent, by Angus ChemicalCompany under the trade designation AMICAL 48 fungi growth-inhibitingagent, and by Healthshield Technologies, LLC. under the tradedesignation HEALTHSHIELD fungi growth-inhibiting agent.

Preferably, the closed cell foam layer 24 on the fibrous pipe insulationsections 20 has a water vapor permeance rating of 0.02grains/ft²·hour·inch Hg or less (0.02 perms or less) as measured by“Standard Test Methods for Water Vapor Transmission of Materials”, ASTMDesignation E 96-00, approved Apr. 10, 2000, and, more preferably,functions as a water vapor barrier to prevent water vapor transmissionthrough the closed cell foam layer 24 into the fibrous core 22. It iscurrently believed that a closed cell foam layer 24 that is about 0.25inches in thickness will provide the closed cell foam layer 24 with thedesired water vapor transmission characteristic of 0.02 perms or less.For certain applications, it is contemplated that the closed cell foamlayer 24 may have a water vapor permeance rating greater than 0.02 permsin which case the thickness of the closed cell foam layer 24 may beadjusted to achieve the desired water vapor permeance rating.

The coated fibrous pipe insulation sections 20 may be held and sealedabout a pipe with an adhesive strip 34 as shown in FIG. 2 that extendsalong the entire length of and bridges the slit 26 or the coated fibrouspipe insulation section 20 may be held and sealed about a pipe with asolvent weld that extends along the entire length of the slit 26 andbridges the slit 26 or an adhesive coating 36 that extends along theentire length of the slit 26 bonding the opposed surfaces of the slit 26together as shown in FIG. 3. Preferably, the closed cell foam layer 24of a coated fibrous pipe insulation section 20, as applied to and sealedabout a pipe 32, e.g. with an adhesive strip 34, a solvent weld, or anadhesive coating 36, has a water vapor permeance rating of 0.02 perms orless and, more preferably, functions as a water vapor barrier so that anauxiliary PVC jacket is not required to prevent the passage of watervapor into the core 22 when using the coated fibrous pipe insulationsection 20 to insulate a cold pipe system.

Preferably, the coated fibrous pipe insulation sections 20 have athickness and thermal conductivity, for a temperature between 35° F. and65° F. at the inner surface of the core 22 (a cold pipe system) and atemperature of 90° F. and a relative humidity of 90% at the outersurface of the core 22, that locates the dew point within the wall ofthe core 22 as schematically shown in FIG. 4. As shown in FIG. 4, thedew point is located along a dashed line 38 that is spaced inward fromthe outer surface of the core wall and outward from the inner surface ofthe core wall so that condensation does not occur on the outside of core22 to cause water damage or encourage microbial growth or on the insidesurface of the core 22 to contribute to corrosion of the pipe 32.

In describing the invention, certain embodiments have been used toillustrate the invention and the practices thereof. However, theinvention is not limited to these specific embodiments as otherembodiments and modifications within the spirit of the invention willreadily occur to those skilled in the art on reading this specification.Thus, the invention is not intended to be limited to the specificembodiments disclosed, but is to be limited only by the claims appendedhereto.

1. A fibrous pipe insulation system, comprising: a tubular core offibrous insulation having a length and a longitudinal axis; the tubularcore having a substantially cylindrical outer surface; the tubular corehaving a substantially cylindrical inner surface; the tubular corehaving a wall extending between the cylindrical outer surface and thecylindrical inner surface; the wall of the tubular core having aradially extending thickness; the wall of the tubular core having afirst slit extending completely there through; the first slit extendingparallel to the longitudinal axis of the tubular core for the length ofthe tubular core; the tubular core having a second slit in the innersurface of the tubular core; the second slit being substantiallyopposite the first slit; the second slit extending parallel to thelongitudinal axis of the tubular core for the length of the tubularcore; and the second slit extending only partially through the wall ofthe tubular core to form a longitudinally extending hinge in the tubularcore that permits the tubular core to be opened and closed to place thetubular core about a pipe; and a closed cell foam layer coextensive withand bonded to the substantially cylindrical outer surface of the tubularcore; the closed cell foam layer being flexible so that the tubular corewith the closed cell foam layer can be opened, placed about a pipe, andclosed without cracking the closed cell foam layer; and thesubstantially cylindrical outer surface of the core has a first radius;the substantially cylindrical inner surface of the core has a secondradius; and for a temperature at the substantially cylindrical innersurface of the core between 35° F. and 65° F. and a temperature of 90°F. and a relative humidity of 90% at the substantially cylindrical outersurface of the core, a dew point temperature is attained within the wallof the core at a radial distance less than the first radius and spacedinwardly from the substantially cylindrical outer wall of the core andgreater than the second radius and spaced outwardly from thesubstantially cylindrical inner wall of the core.
 2. The fibrous pipeinsulation system according to claim 1, wherein: the closed cell foamlayer has a water vapor permeance rating of 0.02 perms or less.
 3. Thefibrous pipe insulation system according to claim 1, including: sealingmeans for sealing the first slit so that when the first slit is sealedby the sealing means an outer surface layer of the sealed fibrous pipeinsulation system comprising the closed cell foam layer and the sealingmeans has a water vapor permeance rating of 0.02 perms or less.
 4. Thefibrous pipe insulation system according to claim 3, wherein: thesealing means is a strip with an adhesive surface for bonding the tapeto the closed cell foam layer.
 5. The fibrous pipe insulation systemaccording to claim 3, wherein: the sealing means is an adhesive forclosing the first slit and bonding opposing surfaces of the closed cellfoam layer and first slit together.
 6. The fibrous pipe insulationsystem according to claim 1, wherein: the thickness of the core wall isbetween 0.5 and 6 inches.
 7. The fibrous pipe insulation systemaccording to claim 1, wherein: the thickness of the core wall is between0.5 and 6 inches; and the second slit has a depth between 0.5 and 0.75of the core wall thickness.
 8. The fibrous pipe insulation systemaccording to claim 1, wherein: the tubular core of fibrous insulationsystem is a tubular core of fiberglass insulation; and the length of thetubular core is about 36 inches, the thickness of the wall of thetubular core is between about 0.5 inches and 6 inches, and the tubularcore fits pipes having nominal diameters between about 0.5 inches and 30inches.
 9. The fibrous pipe insulation system according to claim 1,wherein: the closed cell foam layer is a water vapor barrier thatprevents the passage of water vapor through the closed cell foam layerinto the tubular core.
 10. The fibrous pipe insulation system accordingto claim 9, including: sealing means for sealing the first slit so thatwhen the first slit is sealed by the sealing means an outer surfacelayer of the sealed fibrous pipe insulation system, comprising theclosed cell foam layer and the sealing means, is a water vapor barrierthat prevents the passage of water vapor through the closed cell foamlayer and the sealing means into the tubular core.
 11. The fibrous pipeinsulation system according to claim 10, wherein: the sealing means is astrip with an adhesive surface for bonding the tape to the closed cellfoam layer.
 12. The fibrous pipe insulation system according to claim10, wherein: the sealing means is an adhesive for closing the first slitand bonding opposing surfaces of the closed cell foam layer and firstslit together.
 13. The fibrous pipe insulation system according to claim9, wherein: the thickness of the core wall is between 0.5 and 6 inches.14. The fibrous pipe insulation system according to claim 9, wherein:the thickness of the core wall is between 0.5 and 6 inches; and thesecond slit has a depth between 0.5 and 0.75 of the core wall thickness.15. The fibrous pipe insulation system according to claim 9, wherein:the tubular core of fibrous insulation is a tubular core of fiberglassinsulation; and the length of the tubular core is about 36 inches, thethickness of the wall of the tubular core is between about 0.5 inchesand 6 inches, and the tubular care fits pipes having nominal diametersbetween about 0.5 inches and 30 inches.